Digestive Health Inflammatory Bowel Disease Treatment Side Effects of Flagyl (Metronidazole) This antibiotic is used to treat infections and pouchitis in j-pouches By Amber J. Tresca Amber J. Tresca Facebook LinkedIn Twitter Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. She was diagnosed with ulcerative colitis at age 16. Learn about our editorial process Updated on August 10, 2022 Medically reviewed by Suzanne Fisher, MS, RD, LDN Medically reviewed by Suzanne Fisher, MS, RD, LDN Suzanne Fisher, RD, founder of Fisher Nutrition Systems, has been a board-certified registered dietitian and licensed nutritionist for over 30 years. Learn about our Medical Expert Board Fact checked by Nick Blackmer Fact checked by Nick Blackmer LinkedIn Nick Blackmer is a librarian, fact-checker, and researcher with more than 20 years’ experience in consumer-oriented health and wellness content. Learn about our editorial process Print Table of Contents View All Table of Contents Uses Common Side Effects Check With Your Healthcare Provider Other Important Considerations Flagyl is a type of antibiotic and an antiprotozoal medication that is used to treat bacterial infections in the body. The generic name for this antibiotic is metronidazole, and it also may be sold under names such as Metrogel, Metrolotion, Noritate, Nuvessa, and Vandazole. Flagyl may be used to treat infections occurring in the skin, reproductive organs, and the digestive tract. It is often taken as a capsule, but it can also be applied topically or vaginally, or administered as an IV in a hospital or healthcare provider’s office. Verywell / Gary Ferster Uses Flagyl is sometimes used to treat Crohn’s disease, which is one form of inflammatory bowel disease (IBD), especially when the disease is affecting the perianal area or only the colon (large intestine). It may also be used to treat pouchitis, which is a poorly-understood condition that occurs in people who have had surgery to remove their large intestine and create an internal pouch from the small intestine, which is called a j-pouch. Pouchitis tends to occur more often in people who had the surgery to treat ulcerative colitis than in people who had the surgery to treat another condition in the colon, such as familial adenomatous polyposis (FAP). Flagyl is also used to treat an infection in the digestive tract with a bacteria called Clostridioides difficile (formerly called Clostridium difficile, commonly called C. diff). C. diff infections are becoming increasingly prevalent and are especially dangerous when they occur in people who have IBD. For treating pouchitis and C. diff, Flagyl is sometimes taken for long periods of time, and perhaps along with another antibiotic, or alternating with another antibiotic. Flagyl is also used in combination with other drugs to treat an infection with Helicobacter pylori. H. pylori infects the stomach and can lead to stomach ulcers. Flagyl And Alcohol It is extremely important that people who take Flagyl not drink alcoholic beverages until at least 3 days after stopping the drug. Flagyl affects the way alcohol is broken down, and that leads to symptoms of nausea and vomiting, which can be severe. Common Side Effects Check with your healthcare provider if any of the following side effects continue or are bothersome: diarrheadizziness or light-headednessheadacheloss of appetitenausea or vomitingstomach pain or crampsunpleasant or sharp metallic taste Check With Your Healthcare Provider Check with your healthcare provider if you have any of the following side effects, which may be caused by hypersensitivity to the medication: any vaginal irritation, discharge, or dryness not present before use of this medicinedryness of the mouthclumsiness or unsteadinessmood or other mental changesskin rash, hives, redness, or itchingsore throat and feverstomach and back pain (severe) For injection form: Pain, tenderness, redness, or swelling over the vein in which the medicine is given Notify Your Healthcare Provider Immediately It’s not common, but some people experience a tingling in their hands and feet when taking Flagyl. If that happens, stop taking the drug immediately and call the healthcare provider to figure out what to do next.Less common: Numbness, tingling, pain, or weakness in hands or feetRare: Convulsions (seizures) Other Important Considerations All antibiotics can reduce the effectiveness of oral contraceptives (“the pill”), so women using this as their birth control method should use a backup method until after finishing the course of antibiotics. Flagyl can also sometimes cause urine to turn dark brown, but this is not dangerous and it goes away after the drug is stopped. Flagyl, and all other antibiotics, should always be taken until the prescribed dose is finished. If there are concerns about the potential adverse effects of this or any other drug, check with a pharmacist and/or healthcare provider before discontinuing it. Other side effects not listed above may also occur in some patients. Check with a healthcare provider about any other effects that occur. This information is meant only as a guideline—always consult a healthcare provider or pharmacist for complete information about prescription medications. 3 Sources Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Schieffer KM, Williams ED, Yochum GS, Koltun WA. Review article: the pathogenesis of pouchitis. Aliment Pharmacol Ther. 2016;44(8):817-835. doi:10.1111/apt.13780 Chey WD, Leontiadis GI, Howden CW, Moss SF. ACG clinical guideline: treatment of Helicobacter pylori infection. Am J Gastroenterol. 2017;112(2):212-239. doi:10.1038/ajg.2016.563 National Library of Medicine. DailyMed. FLAGYL- metronidazole tablet, film coated [drug label]. By Amber J. Tresca Amber J. Tresca is a freelance writer and speaker who covers digestive conditions, including IBD. 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